I'll break his response down into two parts. The first being the innitial reaction:
I think that would be pretty impossible -laughs-
To me, this sounds like his views on Ridley (for some reason) are that he's unplayable material only. However, his tone seems to change after the initial laugh is over. He says:
We may have been able to do it, but he might have been a little slow, is that alright? -laughs again-
This second sentence really is the reason I'm hopeful for Ridley. He's almost completely changed his tune about Ridley. He went from saying it's impossible, to asking if a slow playable Ridley is alright. Now, regardless of WHY he changed his tune, he now knows that fans take a playable Ridley seriously, and, he seems to be willing to try it. Without this interview, we would have virtually no insight into how Sakurai feels about Ridley, other than making him: A Background graphic, a villian in the intro, and a Boss/AT.